Without limiting the scope of the invention, its background is described in connection with angular measurement sensors in tiltrotor aircraft.
Precise and accurate measurements of absolute angular positions are necessary in many control and monitoring applications. Many traditional angular measurement sensors are limited in displacement. For example, rotary variable differential transformers (RVDTs) have a maximum angular displacement of around 80°. Resolvers are capable of measuring a complete revolution (360°), but they must be limited to one revolution if an absolute measurement is required, as further rotation of the sensor results in an identical electrical reading for more than one physical angular input. Gear reduction can be used to better match the physical position to be measured to the physical capabilities of the sensor. However, since the electrical output of the sensor is limited, both the accuracy and resolution of the resulting measurement are limited. Similar difficulties exist for obtaining a variety of precise and accurate measurements.
For example, the rotation of the pylon/nacelle in some tiltrotor aircraft is typically measured using a resolver. In one example, the required accuracy is achieved using resolvers, but eight resolvers are needed and the wiring is very complex. In another example, absolute measurement resolvers are used, but each resolver is limited to less than 360 degrees to avoid identical electrical readings for more than one physical measurement, enabling absolute measurements but limiting precision and accuracy.
Thus, a need exists for methods and systems for measurement of precise and accurate measurements that are better than measurements available with sensors that are limited in displacement.